From the international patent application WO 02/27991 A1 a method for adaptive packet bundling is known. Said application teaches to check system performance parameters, while a system is in operation and to increase or decrease the size of a packet based on said system parameters. Processor utilisation, delay time and jitter are checked as performance parameters for determining the optimal packet size. The delay time is a measure for the time it takes for a packet to travel from a source to a destination. The interval for evaluating the packet size is controlled to prevent system instability and race conditions. The advantage of the method disclosed in that international application is the optimisation of the system performance.
The capability to bundle multiple user messages e.g. into one internet protocol IP-packet as provided by message oriented transport protocols, such as the stream control transmission protocol SCTP may advantageously result in a more efficient transport of the messages. Said advantage results because on one hand the bandwidths efficiency is improved and on the other hand a per-packet-processing is reduced.
The bandwidth efficiency is improved because the number of packets and consequently also the overhead caused by packet headers etc. are reduced if multiple user messages are bundled into one packet. Furthermore, there may be beneficial secondary effects, such as a reduced number of acknowledgements because more data can be acknowledged at a time by the receiver when receiving packets with multiple bundled messages.
The per-packet processing is reduced due to the lower number of packets needed to transport a given amount of user messages. This can significantly ease the load on nodes such as a sender, a receiver or intermediate routers. If any such nodes are CPU limited, it can help to improve the achievable user data throughput.
In order to perform user message bundling, a transport protocol needs to wait for a bundling delay time until multiple messages have been provided by an upper layer, e.g. an application layer before it can assemble and send a packet. To maximize the bandwidth efficiency, the bundling delay time should ideally be sufficiently long to accumulate enough data to fill a packet having a predetermined maximum size, as e.g. determined by the maximum transfer unit MTU in IP-networks. However, waiting for the bundling delay time causes an additional delay time for the individually received messages before they are sent to another node. Hence, the determination of the bundling delay time requires a trade-off between maximizing the bundling efficiency and keeping the additional delay time for the messages low.
Accordingly, bundling strategies may have the disadvantage that the resulting bundling efficiency is too low or the resulting additional delay time for the received messages before being forwarded is too long.